Cognitive Function In Healthy Adults Research Articles

Effects of Tai Chi and Western Exercise on Physical and Cognitive Functioning in Healthy Community-Dwelling Older Adults

To compare the effects of Tai Chi (TC, n = 37) and Western exercise (WE, n = 39) with an attention-control group (C, n = 56) on physical and cognitive functioning in healthy adults age 69 +/- 5.8 yr, in a 2-phase randomized trial. TC and WE involved combined class and home-based protocols. Physical functioning included balance, strength, flexibility, and cardiorespiratory endurance. Cognitive functioning included semantic fluency and digit-span tests. Data were analyzed using intention-to-treat analysis. At 6 mo, WE had greater improvements in upper body flexibility (F = 4.67, p = .01) than TC and C. TC had greater improvements in balance (F = 3.36, p = .04) and a cognitive-function measure (F = 7.75, p < .001) than WE and C. The differential cognitive-function improvements observed in TC were maintained through 12 mo. The TC and WE interventions resulted in differential improvements in physical functioning among generally healthy older adults. TC led to improvement in an indicator of cognitive functioning that was maintained through 12 mo.

A comparison of statistical approaches used to evaluate change in cognitive function following pharmacologic challenge: an example with lorazepam

Neuropsychological tests are commonly used in psychopharmacological research to understand the nature and the magnitude of cognitive effects of licensed and novel compounds. While the science of cognitive change assessment has advanced considerably, statistical techniques used to guide inferences about differences in cognitive change have not been considered in the same detail, especially in light of recent advances in modeling repeated data. Data from a randomized, placebo-controlled, crossover study of the effect of an acute dose of lorazepam on cognitive function in healthy adults were analyzed using five statistical approaches (paired sample t-test, area under curve (AUC), repeated measures analysis of variance (ANOVA), change from baseline, and linear mixed models (LMM)). Results of significance tests and effect sizes were compared at maximum concentration (C(max)) and over the ascending slopes of cognitive performance. LMM approaches were superior to other statistical approaches with respect to results of significance testing and magnitudes of estimated effect size change. Results of this study suggest that employment of LMM, which permit examination of specific fixed effects (e.g., time, treatment, treatment x time) and that are not confounded by between-subject variability, provide a sensitive approach to detecting the cognitive effects of pharmacologic challenges, even with small samples.

Motor Tests and Cognition in Healthy Older Adults

The Finger Tapping Test (FTT) and Grooved Pegboard Test (GPT) are commonly used in neuropsychological assessments. The performance of healthy older adults on these tasks has not been well characterized in the existing literature. The present study examines FTT and GPT performance in a sample of 307 community-dwelling older individuals (ages 55–74) with no neurological or psychiatric history. Results: FTT performance was influenced by age, gender, and education, while GPT performance was influenced by age and gender. Findings are presented for both hands, as well as dominant-to-non-dominant hand ratio score, on each test. Correlations with other neuropsychological measures demonstrated that the GPT is more strongly correlated with measures of most domains (memory, processing speed, executive functioning, and spatial organization) than the FTT. Conclusions: While the FTT can be used to measure upper extremity motor ability, the GPT may be more strongly associated with general cognitive functioning in healthy adults. The FTT and GPT results presented will improve the utility of these tasks in clinical assessments of older adults.

Schizotypal traits and cognitive function in healthy adults

Growing evidence has shown that psychometrically identified schizotypes among student populations have subtle cognitive impairments in several domains such as attention, working memory and executive function, but the possible association between psychometric schizotypy in adult populations and cognitive function has not been well documented. Here we examined the association between schizotypal traits as assessed by the Schizotypal Personality Questionnaire (SPQ) and cognitive function including memory, attention, executive function, and general intelligence in 124 healthy adults. Cognitive functioning was assessed with the Wechsler Memory Scale-Revised (WMS-R), the Wechsler Adult Intelligence Scale-Revised (WAIS-R), and the Wisconsin Card Sorting Test (WCST). SPQ scores showed a significant inverse correlation with verbal IQ and the information, comprehension and similarities subtests. No correlation was found between SPQ scores and memory, attention, performance IQ, or executive functioning. These results indicate that schizotypal traits in healthy adults are associated with verbal IQ decrements, suggesting that schizotypal traits themselves, even at a non-clinical level, may play unfavorable roles in cognitive functioning, which is in line with the viewpoint that schizotypy is on a continuum with normality, with its extreme form being clinically expressed as schizophrenia.

Gender-Specific Effects of the Catechol-O-MethyltransferaseVal108/158MetPolymorphism on Cognitive Function in Children

The study aimed to determine the cognitive effect of the Val108/158Met polymorphism in the catechol-O-methyltransferase (COMT) gene in children before and during puberty. This polymorphism affects cognitive function in healthy adults and may contribute to risk for schizophrenia. COMT genotype was determined for 8,707 children from the Avon Longitudinal Study of Parents and Children (ALSPAC), a geographically defined general population cohort of children born between April 1, 1991, and Dec. 31, 1992, in the southwest of England. Fourteen measures of cognitive function--including working memory, verbal and motor inhibition, attentional control, and IQ--were assessed at ages 8 and 10 years. Any pubertal development at age 9 years was reported by parents. Effects of COMT genotype on cognition and interactions with gender and puberty were assessed using general linear models. In boys, genotype significantly affected executive function and explained up to 10 points normal variation in verbal IQ. The effects on IQ were significantly greater in pubertal than in prepubertal boys. In girls, there were no significant effects of genotype on cognition. This common polymorphism may be one of the genes of small effect that contribute to normal variation in IQ. The gender-specific nature of the effect and its possible interaction with puberty may be relevant to both normal cognitive and brain development and to abnormal development in disorders such as schizophrenia.

The Relationship Between Frontal Gray Matter Volume and Cognition Varies Across the Healthy Adult Lifespan

Age-associated decline in gray matter brain volume and cognitive function in healthy adults has been reported in the literature. The goal of the current study is to examine the relationship between age-related changes in regional gray matter volumes and cognitive function in a large, cross-sectional sample of healthy adults across the lifespan. Magnetic resonance imaging and cognitive assessment were conducted on 148 adults aged 21-76 years. Multiple regression analyses examining the effect of age were performed on magnetic resonance image-derived gray matter brain volumes and standardized cognitive summary scores of attention and executive function. Regression was also performed to test the effect of age, gray matter volumes, and their interaction on the prediction of cognitive performance. Age significantly predicted performance on tests of attention (F [1, 146]=50.97, p <0.01, R2=0.26) and executive function (F [1, 146]=126.19, p <0.01, R2=0.46) and gray matter volumes for frontal subregions (lateral, medial, orbital), hippocampus, amygdala, and putamen (F [2, 145]=45.34-23.96, p <0.01-0.02). Lateral frontal (beta=-1.53, t=-2.16, df=131, p <0.03) and orbital frontal (beta=1.24, t=2.08, df=131, p <0.04) regions significantly predicted performance on tests of attention. Lateral frontal (beta=-1.69, t=-2.83, df=131, p <0.01) and the interaction between age and lateral frontal volume (beta=3.76, t=2.49, df=131, p <0.02) significantly predicted executive function. The findings confirm age-associated decline in cognitive function and gray matter volumes, particularly in anterior cortical brain regions. Furthermore, the association between lateral frontal gray matter volume and the ability to successfully plan, organize, and execute strategies varies as a function of age across the healthy adult lifespan.

Insulin and cognitive function in humans: experimental data and therapeutic considerations

Data from experimental studies in animals and from epidemiological studies in humans suggest a link between insulin and cognitive performance. Do these results translate into clinical and therapeutic benefit for people with cognitive impairment? Insulin injected peripherally can readily cross the blood–brain barrier. Intravenous insulin can improve aspects of cognitive function in healthy adults and in individuals with Alzheimer's dementia. Moreover, intravenous insulin increases concentrations of a long form of β-amyloid protein, Aβ42. One potential confounding factor with these data, however, is the need for co-administration of glucose with the insulin to maintain euglycaemia as glucose itself can facilitate memory function. Administration of insulin via the intranasal route is scientifically (and therapeutically) more attractive because the insulin goes directly to the cerebrospinal fluid, with minimal systemic absorption; this obviates the need for a glucose infusion. Intranasal insulin may improve some aspects of memory in healthy individuals, but has yet to be studied in people with cognitive impairment. TZDs (thiazolidinediones) reduce peripheral insulin concentrations by enhancing insulin sensitivity. In adults with Type II (non-insulin-dependent) diabetes, TZD therapy improves memory function, but so does sulphonylurea therapy (which elevates peripheral insulin concentrations). Improved memory is linked to lower blood glucose concentrations, rather than altered insulin levels. However, major trials are currently under way examining the impact of TZDs in people with dementia.

Insulin and cognitive function in humans: experimental data and therapeutic considerations

Data from experimental studies in animals and from epidemiological studies in humans suggest a link between insulin and cognitive performance. Do these results translate into clinical and therapeutic benefit for people with cognitive impairment? Insulin injected peripherally can readily cross the blood-brain barrier. Intravenous insulin can improve aspects of cognitive function in healthy adults and in individuals with Alzheimer's dementia. Moreover, intravenous insulin increases concentrations of a long form of beta-amyloid protein, Abeta42. One potential confounding factor with these data, however, is the need for co-administration of glucose with the insulin to maintain euglycaemia as glucose itself can facilitate memory function. Administration of insulin via the intranasal route is scientifically (and therapeutically) more attractive because the insulin goes directly to the cerebrospinal fluid, with minimal systemic absorption; this obviates the need for a glucose infusion. Intranasal insulin may improve some aspects of memory in healthy individuals, but has yet to be studied in people with cognitive impairment. TZDs (thiazolidinediones) reduce peripheral insulin concentrations by enhancing insulin sensitivity. In adults with Type II (non-insulin-dependent) diabetes, TZD therapy improves memory function, but so does sulphonylurea therapy (which elevates peripheral insulin concentrations). Improved memory is linked to lower blood glucose concentrations, rather than altered insulin levels. However, major trials are currently under way examining the impact of TZDs in people with dementia.